News

Farmers Warned about Theileria in Cows

NEW ZEALAND - Dairy farmers are being warned to look for signs of Theileria infection and anaemia in cattle, with severe cases recently reported in the North Island.

DairyNZ chief scientist Dr Eric Hillerton says Theileria orientalis is a parasite transmitted by ticks when they feed on the animal’s blood.

“It’s important farmers are now looking out for this - with heightened risk, particularly in the North Island,” says Eric. “We should stress there is no human or food safety issue and it only affects cattle.

“Ticks are considered the main way of spread of Theileria. It is likely that tick populations increased markedly during last season’s hot, dry summer weather and drought conditions in many parts of New Zealand. The mild winter means they have survived and are now becoming active early.”

Cattle are at risk of infection when moved to areas where infected ticks are present. Likewise, if an infected animal is transported, it can spread infection to ticks in the new location, in turn spreading disease to uninfected animals.

Tests by the Ministry for Primary Industries (MPI) identified the presence of a Theileria orientalis strain called Ikeda. This strain has been associated with anaemia in cattle in Australia and Asia. Theileria orientalis has been present in New Zealand for about 30 years and is in many countries around the world.

MPI and the beef and dairy industry bodies are monitoring the situation closely. MPI is working to increase knowledge of the disease and facilitate access to information and treatments. Vets are also aware of the situation.

The signs of anaemia in cattle include lethargy, pale mucous membranes, exercise intolerance, and increased respiratory and heart rates. Stress and movement of affected animals should be minimised, as their reduced capacity to transport oxygen around the body can lead to collapse and death.

“Exercise intolerance will be likely - farmers may notice animals lagging behind the rest of the mob when being shifted or lying down in the paddock,” says Eric. Affected animals should be rested, given high quality feed and water, and handled only when absolutely necessary.

Farmers who suspect they have animals with anaemia should contact a veterinarian for advice. Farmers in all parts of New Zealand are at risk of having cows with Theileriosis - particularly farms which have had cattle movement in the North Island. To date, the affected areas include Northland, the Waikato, King Country, Bay of Plenty and parts of the lower North Island.

Farmers should be regularly checking their stock for ticks and treating animals as necessary.

Eric says control of ticks is strongly advised. “There is no vaccine and only limited supplies of drugs for treatment of Theileriosis. Risk of the disease is minimised by good stock management and applying tick control when necessary, especially if moving animals (including calves) off-farm or purchasing new cows.”

The recent Theileriosis cases were first picked up in Northland in spring 2012, followed by further cases occurring in south Auckland, Waikato and Bay of Plenty in April. Most cases are associated with cattle movement.

For more information and a full fact sheet on Theileria, visit www.dairynz.co.nz/animalhealth.